1. Field of the Invention
The present disclosure relates to a touch screen panel. More specifically, the present disclosure relates to a touch screen panel that has reduced RC-delay, good visibility, good touch sensitivity and flexibility, and a touch screen-integrated display device.
2. Description of the Related Art
A touch screen penal is a device that senses a user's touch input on a display device. Such a touch screen panel is widely employed in personal handheld devices such as smart phones and tablet PCs, as well as in large display devices such as display devices placed in public facilities and smart TVs.
A typical touch screen panel is attached on the screen of a display device. Since such a touch screen panel is attached on the outer surface of the screen of a display device as an additional panel, the overall thickness of the display device is increased. As a result, the visibility of the display device may be impaired due to the increased thickness.
In order to overcome the above shortcoming, a touch screen-integrated display device of an in-cell type has been recently developed, in which a touch screen panel is integrated within a display device. But, since a touch screen-integrated display device has been developed as an in-cell type, there are several problems.
FIG. 1 is a plan view for illustrating a general touch screen panel. Referring to FIG. 1, the touch screen panel 100 includes a plurality of first touch electrodes 130 and a plurality of second touch electrodes 140 extending in different directions, and connection electrodes 170 connecting the separated first touch electrodes 130 at intersections of the first touch electrodes 130 and the second touch electrodes 140.
In order to prevent the visibility of the display device from deteriorating, the first touch electrodes 130 and the second touch electrodes 140 may be made of a transparent conductive material, such as indium tin oxide (ITO). However, a transparent conductive material has higher electric resistance than those made of metal. Accordingly, RC-delay of the touch screen panel 100 becomes higher. In addition, transparent conductive material such as ITO is less flexible than metal, and thus is not very useful for flexible display devices. Incidentally, as touch screen panels become thinner, as touch electrodes dispose closer to other electrodes in panel, parasitic capacitance is increased and accordingly, RC-delay becomes higher. Therefore, it is very difficult to reduce the thickness of a touch screen-integrated display device of an in-cell type using touch electrodes made of a transparent conductive material.
To address the shortcomings, a technique has been proposed to make the first touch electrodes 130 and the second touch electrodes 140 with metal electrodes in a mesh pattern. However, metal electrodes exhibit have a limitation of increasing area to hold capacitance for sensing touch compared to that of the plane electrodes made of a transparent conductive material, so that the touch sensitivity of the touch screen panel deteriorates. In addition, since metal materials reflect light, metal electrodes in a mesh pattern are dimly seen, i.e., so-called moiré pattern is observed. Accordingly, optical properties are impaired.